Titanium-Aluminum Alloy

ABSTRACT

The invention relates to a titanium/aluminium alloy with an alloy composed of titanium, aluminium and niobium, with an aluminium content of between 35 and 60 wt. %. The alloy can further contain 1-100 ppm chlorine and/or fluorine and 0.01-1.0 wt. % gold and/or silver. The invention further relates to a lightweight component made from a titanium/aluminium alloy and the use of a titanium/aluminium alloy for the production of a homogeneous, fine-grain, precursor by means of a spin casting method.

The present invention relates to a titanium-aluminum alloy with an alloy composition of titanium, aluminum and niobium. The invention further relates to a lightweight component made of a titanium-aluminum alloy and the use of a titanium-aluminum alloy for the production of a homogenous, fine-grained precursor material via a centrifugal casting method.

Alloy compositions of titanium, aluminum and niobium are known. Such alloys are used in particular for the production of high-temperature-resistant lightweight components which, on the one hand, have a very low weight and which, on the other hand, must have a high degree of strength. DE 197 35 841 A1 describes an alloy based on titanium aluminides with an alloy composition of titanium, aluminum and niobium. The portion of niobium can vary in the known alloy, namely between 5 and 10 atom-%. In this connection the disclosed alloys always have a portion of 45 atom-% of aluminum. This corresponds to an aluminum portion between 28 and 30% in weight. DE 200 19 886 U1 also describes an alloy based on the production of titanium aluminides using melting and powder metallurgic techniques with an alloy composition of titanium, aluminum and niobium, wherein the aluminum content of the alloy is between 45.5 and 49 atom-%. The niobium content in this known alloy can be between 4 and 10 atom-%. This alloy also has an aluminum portion between 28 and 30% in weight. A niobium-modified titanium-aluminum alloy is known from DE 40 37 959 A1 which alloy substantially consists of titanium, aluminum and niobium, wherein the alloys have 37 to 48 atom-% of titanium, 46 to 49 atom-% of aluminum and 6 to 14 atom-% of niobium. This corresponds to a composition of the alloy of 54 to 36.5% in weight of titanium, 30% in weight of aluminum and 6.5 to 16% in weight of niobium. Finally an alloy composition of titanium, aluminum and niobium is known from U.S. Pat. No. 4,294,615 which alloy composition consists of 58.8% in weight of titanium, 29.8% in weight of aluminum and 11.4% in weight of niobium.

However, the disadvantage of these known alloys of titanium and aluminum is their low temperature resistance with regard to creeping, fatigue and oxidation resistance. In addition, due to their brittleness, the known alloys are particularly difficult to process, in particular processing procedures such as casting or forging.

It is thus an object of this invention to provide a titanium-aluminum alloy with an alloy composition of titanium, aluminum and niobium which does not have these disadvantages, i.e., an alloy which has a high temperature resistance regarding creeping, fatigue, i.e., strength and oxidation resistance.

Furthermore it is an object of this invention to provide lightweight components which have the mentioned high temperature resistance.

These objects are solved by a titanium-aluminum alloy according to the features of claim 1 and a lightweight component according to the features of claim 11.

Advantageous embodiments of the titanium-aluminum alloy according to the invention are described in the dependent claims.

A titanium-aluminum alloy according to the invention with an alloy composition of titanium, aluminum and niobium has an aluminum content between 35 and 60% in weight. The advantage of the alloy according to the invention is that the higher portions of aluminum in comparison to the previously known alloy compositions of titanium, aluminum and niobium achieve an unexpectedly high degree of strength and/or temperature resistance with regard to creeping, fatigue and a corresponding oxidation resistance. In an advantageous embodiment the aluminum content of the alloy is between 43 and 45% in weight. Advantageously the niobium content of the alloy is between 2 and 16% in weight, preferably between 6 and 12% in weight.

In a further advantageous embodiment of the titanium-aluminum alloy according to the invention the alloy contains at least one halogen, in particular portions of chlorine and/or fluorine. The addition of chlorine and/or fluorine advantageously leads to a higher oxidation resistance of the alloy. In this connection the chlorine content and/or fluorine content is between 1 and 100 ppm, preferably between 2 and 10 ppm.

In a further advantageous embodiment the titanium-aluminum alloy according to the invention contains these portions of gold and/or silver. The addition of gold and/or silver also leads to a higher oxidation resistance of the alloy. In this connection the gold content and/or silver content is between 0.01 and 2.0% in weight, preferably between 0.01 and 1.0% in weight.

With the described titanium-aluminum alloys according to the invention an increased strength to 400 to 600 MPa/R.T. at 800° C. can be achieved. The oxidation resistance for 800° C. is 10,000 hours. In addition the alloys according to the invention can be processed very well, i.e. crack-free extruding and forging, segregation-free melting and casting are possible.

Lightweight components made from a titanium-aluminum alloy according to the previously described compositions also have a high temperature resistance, in particular regarding fatigue and oxidation resistance, as well as a high degree of strength.

A titanium-aluminum alloy according to the invention according to the previously described exemplary compositions can be used to produce a homogeneous, fine-grained, precursor material via a centrifugal casting procedure. This is made possible by the very good processability of the alloy compositions according to the invention. 

1. Titanium-aluminum alloy with an alloy composition of titanium, aluminum and niobium, characterized in that the aluminum content of the alloy is between 35 and 60% in weight.
 2. Titanium-aluminum alloy according to claim 1, characterized in that the aluminum content of the alloy is between 43 and 45% in weight.
 3. Titanium-aluminum alloy according to claim 1 or 2, characterized in that the niobium content of the alloy is between 2 and 16% in weight.
 4. Titanium-aluminum alloy according to claim 3, characterized in that the niobium content of the alloy is between 6 and 12% in weight.
 5. Titanium-aluminum alloy according to one of the preceding claims, characterized in that the alloy contains at least one halogen.
 6. Titanium-aluminum alloy according to one of the preceding claims, characterized in that the alloy contains chlorine and/or fluorine.
 7. Titanium-aluminum alloy according to claim 6, characterized in that the chlorine content and/or fluorine content is between 1 and 100 ppm.
 8. Titanium-aluminum alloy according to claim 7, characterized in that the chlorine content and/or fluorine content is between 2 and 10 ppm.
 9. Titanium-aluminum alloy according to one of the preceding claims, characterized in that the alloy contains gold and/or silver.
 10. Titanium-aluminum alloy according to claim 9, characterized in that the gold content and/or silver content is between 0.01 and 2.0% in weight.
 11. Titanium-aluminum alloy according to claim 10, characterized in that the gold content and/or silver content is between 0.01 and 1.0% in weight.
 12. Lightweight component made of a titanium-aluminum alloy according to one of the preceding claims.
 13. Use of a titanium-aluminum alloy according to claims 1 to 11 for the production of a homogeneous, fine-grained precursor material via a centrifugal casting method. 